Cheating may be a man's way of restoring his gender identity when it is under threat, said Christin Munsch, a sociology PhD candidate at Cornell University who presented the report Monday at the annual American Sociological Association meeting. The study found that men who are financially dependent on their wives or girlfriends are five times more likely to cheat. Women who made much less than their male partners were less likely to cheat.
"Men and women react very differently to economic dependency," Munsch told LiveScience.
Munsch surveyed heterosexual couples between the ages of 18 and 28 from 2001 to 2007. She asked three questions: One, whether the person was still in the relationship they'd been in the previous year; two, how many sexual partners the person had in the past year; and three, if the person had sex with strangers in the past year.
Cheating was relatively rare: Only 3.8 percent of men and 1.4 percent of women admitted it. Women became more and more likely to cheat as their income increased in relation to their male partner's. Men, on the other hand, were most likely to cheat if they were economically dependent.
But men were also more likely to cheat if they made much more money than their female partners. Men who made 25 percent more than their partners were the most faithful.
High earners in general were more likely to cheat. The findings held even when age, education level, income, religious attendance and relationship satisfaction were taken into account. Making more money may lead to more opportunities to cheat, Munsch said.
But for low-earning men, the relationship between economic dependency and infidelity disappeared when factors like education, age and relationship satisfaction entered into the mix, suggesting that cheating is a more complex matter than who signs the checks.
"We don't really know what that causal chain looks like and why it exists," Munsch said. "So that finding needs to be interpreted with caution."
Barbara Risman, the head of the sociology department at the University of Illinois Chicago and the executive officer of the Council on Contemporary Families, told LiveScience that the study "shows that men are still uncomfortable when they're economically dependent on their wives."
But Stephanie Coontz, a professor of history and family studies at The Evergreen State College in Washington state, told the site: "The take-home message for me out of this is more encouraging for women: Yes, there are guys who still take advantage. But if you are married to a guy who does work, shares your values and background, is close to the same age, and is a good partner, you should not worry at all if you make more than he does!"